Well of course is there is no real yes or no and no right or wrong to it.
IMO while it is always advisable to use the highest quality PA system you can reasonably afford ( the weakest link factor). As far as what the particular pieces that may entail, is strictly a matter of what kind of ( Sound) the individual wants to achieve vs what level of complexity they are comfortable dealing with.
I personally prefer the sparingly judicious use of reverb, EQ, and compression. Beyond that it think it completely a matter of what the performer likes and is comfortable with.
This is the front end that I use for live gigs.
it is Monster 2500 power conditioner, a 2 channel Langevin (Manley Labs) DVC = Dual Vocal Combo that has Mic Pre,EQ and Limiter and a TC 3000 Stereo FX processor for the Verb. In an SBK 6 space rolling rack
Relatively simple system I plug my guitar and vocal mic into the DVC and plug my system outs into either my Fishman Solo, or the house board or speakers.